64 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



attack other conifers. Many young pines in California have been 

 killed by this scale. It is distributed over most of North America. 

 The mature scales are almost circular, y 16 inch in diameter, 

 and yellowish brown to black. The young hatch early in the spring 

 and summer and settle upon the new needles of the host. From one 

 to three generations are produced during the year, and the winter 

 is passed as half -grown scales. 



A group of scale insects belonging to the genus Matsucoccus is 

 sometimes found to be the cause of tipkilling, branch "flagging," 

 stunting, or needle injury to pines. Larvae and adults are small, 

 oval, yellow to brown, inconspicuous insects which are often ex- 

 tremely difficult to detect because they push themselves beneath 

 the scale of needle fascicles or bury themselves under the bark of 

 twigs and branches, taking on the color of their environment. 

 Some species have caused serious injury to pines over extensive 

 areas. No control methods have been developed. 



The Prescott scale (Matsucoccus vexillorum Morrison) {113, 

 lllf) (fig. 27) has been found causing extensive killing of branches 

 of ponderosa pine in Arizona, New Mexico, and Southwestern 

 Colorado. The motile adult males and females emerge early in the 

 spring. The females settle on twigs, mainly at the nodes of 

 branches, where they lay eggs covering them with a fluffy white 

 wax. Two stages of larvae develop late in the spring and in the 

 summer; they feed beneath scales at the base of needles and in 

 cracks and crevices of twigs, particularly around the first and 

 second nodes. During the fall a third preadult stage develops and 

 then overwinters under needle bracts as purplish, prune-shaped 

 bodies. The life cycle is completed in 1 year. 



Other species of Matsucoccus recorded from western pines in- 

 clude the following: 



Species Hosts 



On needles — conspicuous: 



acalyptus Herbert (104) . . Pinyon, singleleaf, and foxtail pines. California, 



Arizona, New Mexico, Utah, Colorado, and 

 Idaho. 

 Within needle sheath at base of needle bundle: 

 fasciculensis Herbert Ponderosa, Jeffrey, and digger pines. Califor- 

 nia and Oregon. 

 degeneratus Morrison .... Ponderosa pine. Arizona. 



secretus Morrison Ponderosa pine. California, Nevada, Arizona, 



New Mexico, and Colorado. 

 On bark at base of needle bundles, in axils of twigs and branches, and along 

 small branches in crevices of bark: 



vexillorum Morrison See above. 



paucicicatrices Morrison 



(111) Sugar, western white, and limber pines. Cali- 

 fornia, Oregon, Montana, and Wyoming. 



eduli Morrison Pinyon. Arizona. 



monophyllae McKenzie . . . Singleleaf pinyon. California. 

 In cracks and crevices of twigs and under heavy bark: 



bisetosus Morrison (112) . . Ponderosa and Jeffrey pine. California and 



Oregon. 

 calif ornicus Morrison .... Ponderosa pine and Jeffrey pine. California 



and Arizona. 



